Even non-smokers can experience health hazards from cigarette smoke, and the latest study suggests the dangers may depend on your gender.

About 46,000 non-smokers in the U.S. die from heart disease and 3,400 are claimed by lung cancer each year, according to the American Cancer Society. The most likely culprit? Second hand smoke, which studies have linked to increased risk of dementia, high blood pressure, and genetic changes. Now, scientists report in the Journal of Clinical Endocrinology & Metabolism (JCEM) that teen girls may be particularly vulnerable to the effects of such passive exposure. The researchers from the University of Western Australia studied a cohort of 1,057 teens born between 1989 and 1992, and collected information on smoking in the children’s homes from the time their mothers were pregnant to the time the kids were 17. The researchers also collected blood samples to measure the teens’ cholesterol levels at the end of the trial. Over the study period, 48% of the children were exposed to secondhand smoke in their home.

When the scientists compared these cholesterol readings to the adolescents’ smoking exposure, they discovered that teenage girls who grew up in homes where smoking was present were more likely to have lower levels of good HDL cholesterol, which helps to protect against heart disease by clearing cholesterol from the blood. “Assuming causality in these relationships, there are strong public health implications concerning the need to avoid children, particularly girls, being exposed to passive smoking in the household,” the authors write.

Why would girls be especially at risk? The study wasn’t designed to determine what made passive smoke exposure more hazardous for girls over boys, but the researchers do not believe hormones made a difference, since the vast majority of the participants were past puberty. Cigarette smoke may pose particular problems for women’s hearts, however, since previous research showed that smoking leads to a 25% higher risk of heart disease risk among women compared to men. The findings are enough to prompt further research into gender-based differences in the reaction to the components in cigarette smoke — and sufficient to bolster efforts to reduce all children’s exposure to smoking.